Simplify the following expression: $t = \dfrac{3x}{10} - \dfrac{x}{2}$
In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $10$ and $2$ $\lcm(10, 2) = 10$ $ t = \dfrac{1}{1} \cdot \dfrac{3x}{10} - \dfrac{5}{5} \cdot \dfrac{x}{2} $ $t = \dfrac{3x}{10} - \dfrac{5x}{10}$ $t = \dfrac{3x -5x}{10}$ $t = \dfrac{-2x}{10}$ Simplify the expression by dividing the numerator and denominator by 2: $t = \dfrac{-x}{5}$